um/x86: merge (and trim) 32- and 64-bit variants of ptrace.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 4d9af31..3a2235e 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -196,7 +196,7 @@
 	if (current->thread.forking) {
 	  	memcpy(&p->thread.regs.regs, &regs->regs,
 		       sizeof(p->thread.regs.regs));
-		REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
+		UPT_SET_SYSCALL_RETURN(&p->thread.regs.regs, 0);
 		if (sp != 0)
 			REGS_SP(p->thread.regs.regs.gp) = sp;